Variable cross-section stiffener plastic spring for heavy-duty shock absorber

Abstract

This invention belongs to the technical field of automotive shock absorber components and discloses a variable cross-section reinforced plastic spring for heavy-duty shock absorbers. It includes two sets of end mounting sections and multiple sets of joint sections disposed between the two sets of end mounting sections. Reinforcing ribs are connected between each set of joint sections, and the thickness of all reinforcing ribs is distributed in a gradually varying cross-section. A stress relief groove is provided at the external connection between the joint section and the reinforcing rib. This stress relief groove is formed by the inward indentation of the external interface area between the joint section and the reinforcing rib. The outer wall of the stress relief groove has a wavy profile in the circumferential direction, including multiple alternating peaks and troughs, with the outer diameter at the peaks being larger than that at the troughs. This invention, through the synergistic cooperation of the stress relief groove and the wavy profile, discretizes the annular stress concentration zone at the external connection into multiple isolated stress regions, significantly improving the fatigue resistance and load-bearing capacity of the plastic spring under heavy-duty conditions.

Description

Technical Field

[0001] This invention relates to the field of automotive shock absorber components, and more specifically, to a variable cross-section reinforced plastic spring for heavy-duty shock absorbers. Background Technology

[0002] Currently, heavy-duty vehicle shock absorbers widely use plastic springs as the elastic element. Their basic structure is a bellows-like structure composed of multiple stacked annular joints, with reinforcing ribs on the outer wall of the joints. The entire structure is fitted onto the outside of the shock absorber piston rod. During operation, the axial compression and rebound of the joints achieve the shock absorption and cushioning function. Its core function is to replace traditional metal springs, while also offering advantages in lightweight design, corrosion resistance, and cost.

[0003] In the prior art, CN105443631A discloses a compression buffer spring for an automotive shock absorber and its molding die, which has parallel-arranged intermediate ribs, transition ribs, and edge ribs. The ribs are connected by arc-shaped elastic thin walls. The intermediate rib has the largest width, decreasing sequentially towards both ends, and its outer diameter is also the largest, decreasing towards both ends. This design improves material utilization efficiency to some extent through the gradual distribution of rib width.

[0004] However, existing technologies still have the following problems: Firstly, external connections are weak points for fatigue crack initiation: whether it's the connection between the rib and the elastic thin wall, or the connection between the joint segment and the reinforcing rib, existing technologies use simple constant curvature circular arc transitions or smooth inclined plane transitions, only meeting basic smooth connection requirements, without specifically optimizing for the stress distribution characteristics of the connection under heavy-load compression conditions. Under heavy-load alternating loads, external connections bear significant bending stress, which is uniformly and continuously distributed circumferentially, easily forming annular stress concentration zones on the same cross-section, leading to premature fatigue crack initiation. This is one of the key reasons for the insufficient fatigue life of existing plastic springs under heavy-load conditions.

[0005] Secondly, there is a mismatch between load-bearing capacity and stress distribution: Although existing technologies have recognized that variable cross-section design of ribs can improve stress distribution, the thickness changes are simply a sequential decrease from the middle to both ends, with the outer diameter decreasing synchronously. This design logic of "thickness and outer diameter changing in the same direction" does not accurately match the actual load distribution under heavy load conditions, where "the stress at both ends is small and the stress in the middle is large." It fails to identify the stress peak area in the middle of sections 2 and 4, resulting in the most critical areas not being effectively reinforced, while the reinforced areas introduce new interference risks due to their excessively large outer diameter.

[0006] Thirdly, there is the problem of uncontrolled deformation during compression: When existing plastic springs are compressed under heavy loads, the inner diameter of the joint shrinks and deforms due to excessive circumferential stress, resulting in excessive friction with the piston rod or even seizing; at the same time, the expansion of the outer diameter of the joint is not effectively controlled, exceeding the inner diameter of the working cylinder after compression and causing motion interference. The above problems essentially stem from the lack of a constraint mechanism for the radial deformation of the joint segment during compression, making it impossible to control both the shrinkage of the inner diameter and the expansion of the outer diameter.

[0007] Fourth, the rebound performance does not meet the requirements for heavy-duty durability: the connection between the inner wall of the joint and the reinforcing rib is mostly a right-angle transition, which easily causes stress concentration at this point during compression, leading to plastic yielding deformation. After fatigue cycles, the rebound height loss exceeds 30%, which cannot meet the durability requirements of heavy-duty shock absorbers. Summary of the Invention

[0008] The purpose of this invention is to solve the technical problems of short fatigue life, insufficient load-bearing capacity, easy motion interference, and rapid decay of rebound performance of plastic springs under heavy load conditions in the prior art, and to propose a variable cross-section reinforced plastic spring for heavy load shock absorbers.

[0009] To solve the above problems, the present invention adopts the following technical solution: A variable cross-section reinforced plastic spring for heavy-duty shock absorbers includes two sets of end mounting sections, with multiple sets of joint sections arranged sequentially along the axial direction between the two sets of end mounting sections, and each set of joint sections is connected to a reinforcing rib. The thickness of all the aforementioned stiffeners is distributed in a gradually changing cross-section; A stress relief groove is provided at the external connection between the joint segment and the reinforcing rib. The stress relief groove is formed by the inward indentation of the external interface area between the joint segment and the reinforcing rib. The outer wall of the stress relief groove has a wavy profile in the circumferential direction. The wavy profile includes multiple alternating peaks and troughs, and the outer diameter at the peak is larger than the outer diameter at the trough.

[0010] As a further aspect of the present invention, the thickness of all the reinforcing ribs is distributed in a gradually changing cross-section, with the thickness of the reinforcing ribs located in the middle being the greatest, and the thickness of the reinforcing ribs decreasing sequentially from the middle to both ends.

[0011] As a further embodiment of the present invention, the joint segment has four sections, and the reinforcing rib has three ribs, wherein the thickness of the reinforcing rib located in the middle position is greater than the thickness of the reinforcing rib located at the edge position.

[0012] As a further embodiment of the present invention, a reverse R-curve is provided on the inner wall of the joint segment and the reinforcing rib connection, and on the inner wall of the joint segment and the end mounting segment connection. The reverse R-curve smoothly transitions with the inner wall of the joint segment, the reinforcing rib and the end mounting segment to form a continuous stress flow path.

[0013] As a further embodiment of the present invention, the outer wall of the joint segment protrudes radially outward to form a bent portion, and each bent portion is provided with two through holes symmetrical about the center of the joint segment.

[0014] As a further embodiment of the present invention, the through hole is elliptical in shape, and the length direction of the through hole extends laterally along the bend.

[0015] As a further embodiment of the present invention, the thickness of the end mounting section is less than the minimum thickness of the reinforcing rib, all the reinforcing ribs have the same outer diameter, and the outer diameter of the end mounting section is less than the outer diameter of the reinforcing rib.

[0016] As a further embodiment of the present invention, the axial section of the stress relief groove is an arc-shaped groove, a U-shaped groove, or a V-shaped groove, and the root of the V-shaped groove or U-shaped groove is provided with a rounded transition. The transition surface between adjacent peaks and troughs in the wavy profile is a smooth arc surface.

[0017] As a further aspect of the present invention, the radial height difference between the crests and troughs of the wavy profile is 5%-20% of the wall thickness of the joint segment.

[0018] As a further embodiment of the present invention, the joint segment is two segments, and a reinforcing rib is connected between the two joint segments. The thickness of the reinforcing rib is greater than the wall thickness of the joint segment.

[0019] Compared with the prior art, the advantages of this invention are: I. This invention incorporates a stress-relieving groove at the external connection between the joint segment and the reinforcing rib. This guides the stress, originally concentrated on the connection surface, to the bottom of the groove for dispersion, altering the stress transmission path at the connection. Furthermore, a circumferential wavy profile is created on the outer wall of the stress-relieving groove, causing the stress to be distributed with alternating peaks and troughs in the circumferential direction. This discretizes the originally uniform and continuous annular high-stress zone into multiple isolated stress concentration areas. The synergistic effect of these two mechanisms optimizes the stress state at the external connection from "surface concentration" to "volume dispersion," significantly improving the fatigue life of the connection.

[0020] Second, this invention combines the variable cross-sectional thickness distribution of the reinforcing ribs with the equal outer diameter design. While accurately matching the load distribution of "small force at both ends and large force in the middle" under heavy load conditions, it also makes the outer diameter expansion of each segment consistent and controllable, thus achieving a balance between improving load-bearing capacity and controlling deformation.

[0021] Third, this invention manages the stress on the outer wall through stress relief grooves and wavy contours at the external connection, and optimizes the stress flow path on the inner wall through reverse R-arc grooves. The synergistic effect of the inner and outer walls disperses the stress on the outer wall and suppresses the plastic yielding of the inner wall when the spring is compressed under heavy load, thus ensuring the spring's rebound durability.

[0022] In summary, this invention solves the long-standing problem of fatigue cracks at external connections in the field of heavy-duty plastic springs through the innovative combination of "stress relief groove at external connection + circumferential wavy profile". At the same time, through the synergistic cooperation of structures such as variable cross-section reinforcing ribs, constant outer diameter design, and reverse R-curve groove, it systematically improves the load-bearing capacity, deformation control capability, and durability of plastic springs under heavy-duty conditions. The various structural features support each other and work together to produce a comprehensive technical effect that is superior to the prior art. Attached Figure Description

[0023] Figure 1 This is one of the structural schematic diagrams of the present invention (the number of joint segments is four). Figure 2 This is the second structural schematic diagram of the present invention (the number of joint segments is two). Figure 3 For the present invention Figure 2 A half-section view; Figure 4 For the present invention Figure 3 Enlarged view of point A (showing the reverse R-curve); Figure 5 This is a schematic diagram showing the wavy outline of the stress relief groove of the present invention; Figure 6 For the present invention Figure 1 A cross-sectional view (showing that the thickness of the stiffeners is distributed in a gradually changing cross-section).

[0024] Explanation of the labels in the diagram: 1. End mounting section; 2. Joint section; 21. Bending section; 3. Reinforcing rib; 4. Stress relief groove; 5. Reverse R-curve groove; 6. Through hole. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] I. Overall Structure: Please see Figure 1 and Figure 2 The present invention provides a variable cross-section reinforcing plastic spring for heavy-duty shock absorbers, which is an integral injection-molded structure.

[0027] The plastic spring includes two sets of end mounting sections 1, which are located at opposite ends of the plastic spring's axial direction, for mounting the spring to a designated position on the shock absorber. Multiple sets of joint sections 2 are sequentially arranged axially between the two sets of end mounting sections 1.

[0028] As a preferred embodiment of the present invention, such as Figure 1 As shown, there are four joint segments 2, and each joint segment 2 is connected to a reinforcing rib 3. Specifically, there is a first reinforcing rib between the end mounting segment 1 and the joint segment 2, a second reinforcing rib between the second joint segment 2 and the third joint segment 2, and a third reinforcing rib between the third joint segment 2 and the fourth joint segment 2, for a total of three reinforcing ribs 3.

[0029] As another preferred embodiment of the present invention, such as Figure 2 As shown, the number of joint segments 2 is two. Two joint segments 2 are arranged axially between the two sets of end mounting segments 1. A reinforcing rib 3 connects the two joint segments 2. The structure of the two joint segments is suitable for shock absorbers with relatively compact axial space, which reduces the total axial length of the spring while ensuring load-bearing capacity.

[0030] The end mounting sections 1 at both ends are integrally formed with the adjacent joint sections 2, and the transition is smooth, ensuring that the ends will not generate additional stress concentration due to structural abrupt changes when the spring is subjected to force.

[0031] II. Reinforcing Rib Structure: like Figure 3 As shown, the reinforcing rib 3 is a ring-shaped protrusion protruding outward along the radial direction. The outer wall of the reinforcing rib 3 is integrally formed with the joint segment 2 and smoothly transitions. The ring-shaped structure of the reinforcing rib 3 enables it to uniformly bear and transfer loads in the circumferential direction, avoiding excessive local stress. The edges of the reinforcing rib 3 are rounded or beveled, which not only avoids the problem of discomfort during handling and assembly, but more importantly, eliminates stress concentration at sharp corners, thus improving fatigue life.

[0032] like Figure 6As shown, the thickness of the reinforcing rib 3 is distributed in a gradually changing cross section, specifically, the entire cross section is thinner at both ends and thicker in the middle.

[0033] When the joint segment 2 has four segments, the second reinforcing rib in the middle position of the three reinforcing ribs 3 has the largest thickness, while the first and third reinforcing ribs in the edge position have smaller thicknesses, and the thickness of the reinforcing ribs 3 decreases sequentially from the middle to both ends.

[0034] When joint segment 2 is two-segmented, there is only one reinforcing rib 3, and the thickness of the reinforcing rib 3 is greater than the wall thickness of joint segment 2.

[0035] This design is based on the fact that under actual heavy load conditions, stress is mainly concentrated in the middle area of ​​the spring. By thickening this area, a precise match with the actual stress distribution curve is achieved, allowing the material to be used most efficiently.

[0036] All reinforcing ribs 3 have the same outer diameter. This uniform outer diameter design ensures that the outer diameter expansion of each segment is consistent and controllable during compression, keeping the safety gap between each segment and the inner wall of the working cylinder uniform and avoiding local interference.

[0037] III. Stress relief groove structure: Please see Figure 3 A stress relief groove 4 is provided at the external connection between the joint segment 2 and the reinforcing rib 3. The stress relief groove 4 is formed by the inward indentation of the external interface area between the joint segment 2 and the reinforcing rib 3.

[0038] Specifically, in the transition area between the outer wall of joint segment 2 and the outer wall of reinforcing rib 3, the outer wall surfaces are not simply connected by straight lines or arcs, but rather both are concave inwards radially, forming an annular groove structure surrounding the outer wall of the spring. This annular groove breaks the flat transition shape at the external connection, allowing the stress originally concentrated on the connection surface to be guided to the bottom area of ​​the groove for dispersion, thus avoiding stress concentration at sharp corners or abrupt changes on the connection surface.

[0039] 3.1 Axial cross-sectional shape of the stress relief groove: The axial section of the stress relief groove 4 can be an arc-shaped groove, a U-shaped groove, or a V-shaped groove. Wherein: The bottom of the arc-shaped groove is smooth and free of any stress-concentrated sharp corners, ensuring a uniform distribution of stress at the bottom of the groove.

[0040] The two sidewalls of the U-shaped groove are roughly perpendicular to the bottom of the groove, giving the groove a relatively wide bottom area, which can provide a larger area for stress dispersion. The root is provided with an arc transition with a radius of 0.5 mm to 2 mm. The sidewalls smoothly transition with the outer wall of the joint segment 2 and the outer wall of the reinforcing rib 3, ensuring that the stress changes gradually when entering the groove area.

[0041] The two sidewalls of the V-shaped groove are inclined at acute or obtuse angles relative to the bottom of the groove, giving the groove a "wider at the top and narrower at the bottom" shape. The root of the groove has a rounded transition with a radius of 0.3 mm to 1 mm. The two sidewalls smoothly transition to the outer wall of the joint segment 2 and the outer wall of the reinforcing rib 3. Compared with the arc-shaped groove and the U-shaped groove, the V-shaped groove has a more defined stress guiding direction, which can guide the surface stress to the root of the groove more concentratedly, making it suitable for stress optimization under specific load conditions.

[0042] 3.2 Circumferential wavy profile of the stress relief groove: Please see Figure 5 The outer wall of the stress relief groove 4 has a wavy profile in the circumferential direction. The wavy profile includes multiple alternating peaks and troughs, with the outer diameter at the peaks being larger than that at the troughs. The peaks correspond to the shallowest point of the depression in the stress relief groove 4, and the troughs correspond to the deepest point of the depression in the stress relief groove 4.

[0043] This circumferential wavy profile is a further optimization based on the aforementioned annular groove: the stress relief groove 4 itself is an annular groove surrounding the outer wall of the spring. The crest of the wave is the highest point of the bottom surface of the groove, i.e., the shallowest point of the depression, and the trough is the lowest point of the bottom surface of the groove, i.e., the deepest point of the depression. By forming an alternating high and low wavy bottom surface in the circumferential direction, the stress state at various positions in the circumferential direction is no longer uniform when the connection is subjected to compressive load, but rather presents an alternating high and low distribution. This avoids the formation of annular stress concentration zones on the same circumferential cross-section, further improving fatigue resistance.

[0044] In the wavy profile, the transition surface between adjacent crests and troughs is a smooth arc surface, ensuring that the stress changes gently in the transition area between the crests and troughs and does not produce secondary stress concentration.

[0045] The radial height difference between the crests and troughs is 5% to 20% of the wall thickness of joint segment 2. This ratio ensures sufficient stress dispersion without weakening the structural strength of the joint due to excessive concavity. Preferably, the radial height difference between the crests and troughs is 10% of the wall thickness of joint segment 2.

[0046] 3.3 Mechanical principles of wavy profiles: Please see Figure 5 From the perspective of mechanical principles, the aforementioned circumferential wavy profile has the following optimization effect on the stress state of the stress relief groove 4: First, the discretization of stress concentration points: In a traditional circumferentially uniform annular groove structure, the geometry of each cross-section is exactly the same, and the stress is concentrated and evenly distributed at the bottom of the entire annular groove, forming a complete annular high-stress zone. When the spring is subjected to heavy compression, any point in this annular high-stress zone may become the initiation source of fatigue cracks. However, the wavy profile of this invention introduces geometric periodic changes in the circumferential direction, making the groove depth different at different circumferential positions. The stress forms a stress gradient with alternating peaks and troughs in the circumferential direction, discretizing the originally continuous annular high-stress zone into multiple isolated stress concentration regions. Each high-stress point is separated by a relatively low-stress region, reducing the probability of any single location bearing continuous peak stress.

[0047] Second, stress flow redistribution: In a wavy profile, because the depth of the grooves varies periodically in the circumferential direction, the stress flow encounters different geometric constraints at different circumferential positions. At the crests, the grooves are shallower, the stress flow deflection angle is smaller, the path is shorter, and the flow resistance is lower; at the troughs, the grooves are deeper, the stress flow deflection angle is larger, the path is longer, and the flow resistance is higher. Following the physical law of the path of least resistance, the stress flow preferentially chooses to pass through the crest region, thus creating a redistribution of stress flow between the crests and troughs. This reduces the stress flow density at the bottom of the grooves and improves the overall uniformity of stress distribution.

[0048] Third, the deflection hysteresis of crack propagation: For a circumferentially uniform annular groove structure, once a crack initiates at a point on the bottom of the groove, the stress state is basically the same across the entire circumference, and the resistance encountered during circumferential propagation is essentially uniform, allowing the crack to propagate continuously and eventually form a through-crack. However, the wavy profile causes the stress at the bottom of the groove to be distributed alternately in a wave-like pattern along the circumference. As the crack propagates circumferentially, it alternately experiences crests and troughs. When the crack enters a trough, due to the change in groove depth at the trough, the crack propagation direction is no longer perpendicular to the direction of the maximum principal stress, reducing the driving force for crack propagation. Simultaneously, the stress field at the crack tip changes from Type I to Type II or a mixed type, causing the crack propagation path to deflect. Each time the crack crosses a trough, it needs to readjust its direction and consume additional energy, thus reducing the crack propagation rate.

[0049] Fourth, the stress field becomes three-dimensional: the wavy profile introduces circumferential geometric perturbations into the originally axisymmetric two-dimensional stress field, transforming the stress field from a two-dimensional state to a three-dimensional state. Additional shear stress components are generated in the transition region between the crests and troughs. The presence of shear stress changes the direction and magnitude of the principal stresses at the joints, causing the principal stress directions to deflect from the direction most likely to lead to crack propagation, effectively reducing the driving force for crack propagation.

[0050] In summary, the circumferential wavy profile of the outer wall of the stress relief groove 4, through the synergistic effect of four mechanical mechanisms—stress concentration discretization, stress flow redistribution, crack deflection hysteresis, and stress field three-dimensionalization—transforms the originally uniformly continuous high-stress annular band in the circumferential direction into a multi-point stress field with alternating stress distribution in the circumferential direction. This improves the fatigue resistance of the external connection from multiple physical mechanisms. This structural design, in conjunction with the concave structure of the stress relief groove 4, enables the present invention to achieve superior technical effects compared to existing technologies in stress management at external connections.

[0051] IV. Reverse R-groove structure: Please see Figure 3 , 4 A reverse R-groove 5 is provided on the inner wall of the joint segment 2 where it connects to the reinforcing rib 3, and on the inner wall of the joint segment 2 where it connects to the end mounting segment 1.

[0052] Specifically, the reverse R-groove 5 is an arc-shaped groove provided at the transition between the inner wall of the joint and the inner wall of the reinforcing rib or the end mounting section. This arc-shaped groove is recessed in the direction of wall thickness, that is, it is recessed from the inner wall surface of the joint section 2 toward the interior of the wall thickness of the joint section 2, thereby forming an arc-shaped stress guiding surface at the transition. The reverse R-groove 5 smoothly transitions with the inner walls of the joint section 2, the reinforcing rib 3, and the end mounting section 1, forming a continuous stress flow path.

[0053] The curvature direction of this arc-shaped groove is opposite to that of a conventional fillet. A conventional fillet protrudes outward at the corner of the inner wall to eliminate sharp corners, while the reverse R-shaped groove 5 is concave inward. This makes the stress flow of the joint inner wall change from the original abrupt transition to a smooth transition during compression, avoiding stress concentration at the transition point of the inner wall, effectively reducing the plastic yield deformation of the inner wall, and ensuring the rebound performance of the spring after multiple fatigue cycles.

[0054] The radius of the R-angle of the reverse R-groove 5 is optimized based on the material yield strength and compression stroke to ensure that it can achieve the best stress optimization effect under different working conditions.

[0055] V. Bending section and through-hole structure The outer wall of joint segment 2 protrudes radially outward to form a bent portion 21. The bent portion 21 is a local radial protrusion structure provided in the middle area of ​​the outer wall of joint segment 2. It has a certain width in the axial direction and surrounds the entire outer wall of joint segment in the circumferential direction.

[0056] Each bend 21 has two through holes 6 symmetrical about the joint segment 2. The through holes 6 penetrate the wall thickness of the bend 21, connecting the internal space of the spring with the external space. In this embodiment, the through holes 6 are elliptical in shape, and the length of the through holes 6 extends laterally along the bend 21, that is, the major axis of the elliptical through holes is arranged along the circumference of the spring.

[0057] The bend 21 provides more space for the through hole 6, allowing the long axis of the elliptical through hole to extend fully circumferentially. When the spring is compressed, the bend 21 undergoes radial and axial composite deformation along with the joint segment 2, and the elliptical through hole 6 on it opens or closes controllably with the deformation of the bend, thereby actively adjusting the oil flow area and realizing differentiated adjustment of compression damping and rebound damping.

[0058] VI. Stress relief groove at the end mounting section connection: As a further preferred embodiment of the present invention, the stress relief groove 4 is also provided at the external connection between the joint segment 2 and the end mounting segment 1. That is, the external boundary area between the end mounting segment 1 and the adjacent joint segment 2 is recessed inward to form the stress relief groove 4, and the outer wall of the stress relief groove 4 also has a wavy profile in the circumferential direction, including alternating peaks and troughs.

[0059] Since the connection between the end mounting section 1 and the joint section 2 also bears a large bending stress, a stress relief groove 4 is added at the connection of the end mounting section to further eliminate the hidden danger of external stress concentration at both ends of the spring, so that the stress of the external connection of the entire spring is optimized.

[0060] VII. End Mounting Section Dimensions and Modular Design: The thickness of the end mounting section 1 is less than the minimum thickness of the reinforcing rib 3, and the outer diameter of the end mounting section 1 is less than the outer diameter of the reinforcing rib 3. This design makes the end mounting sections 1 at both ends of the spring relatively thin in the radial direction, retaining sufficient radial deformation space, avoiding interference with the end structure of the working cylinder due to the expansion of the outer diameter during compression, while ensuring a safe clearance between the end and the piston rod.

[0061] The height and outer diameter of joint segment 2 are standardized dimensions. Specifically, the joint height and outer diameter form multiple sets of standard dimensions. Different specifications of joint segments have different combinations of height and outer diameter to adapt to working cylinders with different inner diameters and strokes. The joint segments are interconnected through end-capping structures, allowing for switching between different specifications without modifying the overall spring structure, thus achieving true modular design.

[0062] Furthermore, in this embodiment, the plastic spring is integrally injection molded from thermoplastic elastomer material. The injection molding process allows all the aforementioned complex structures, including variable cross-section reinforcing ribs, stress relief grooves and their wavy contours, reverse R-curve grooves, bends, and through holes, to be formed in one step without any post-processing or additional assembly. The material has a sufficiently high tensile modulus and a sufficiently low compressive settling rate to ensure dimensional stability and resilience under heavy loads and high temperatures.

[0063] Working principle: The plastic spring of this invention is fitted onto the outside of the shock absorber piston rod, and its working process is as follows: When a vehicle travels over a bumpy road, the shock absorber is subjected to impact loads, and the plastic spring is compressed axially. During compression, the reinforcing ribs 3 between each joint segment 2 bear the main compressive load. Among them, the reinforcing ribs 3 located in the middle position, due to their greater thickness than those at the edges, provide higher load-bearing capacity in the stress concentration area, effectively preventing central fracture.

[0064] At the same time, the uniform outer diameter design of all reinforcing ribs 3 ensures that the outer diameter expansion of each segment is consistent and controllable during compression, and that the safety clearance between each segment and the inner wall of the working cylinder remains uniform, preventing motion interference caused by local expansion exceeding tolerance.

[0065] At the external connection, the stress relief groove 4 guides the surface stress that was originally concentrated at the junction of the joint segment 2 and the reinforcing rib 3 to the bottom of the groove for dispersion. The wavy circumferential contour further causes the stress to be distributed alternately in the circumferential direction. The two work together to prevent the initiation of fatigue cracks at the connection.

[0066] On the inner wall of the spring, the reverse R-groove 5 optimizes the right-angle transition at the connection between the inner wall of the joint and the reinforcing rib into a smooth stress flow path, reducing the plastic yielding deformation of the inner wall during compression and ensuring the rebound height after multiple fatigue cycles.

[0067] While the spring is compressed, the elliptical through hole 6 on the bent part 21 of the outer wall of the joint section 2 opens and closes in a controllable manner as the bent part deforms, actively adjusting the oil flow area, realizing differentiated adjustment of compression damping and rebound damping, and optimizing the damping characteristics of the shock absorber.

[0068] Because the thickness and outer diameter of the end mounting section 1 are smaller than those of the reinforcing rib 3, it retains sufficient radial deformation space during compression and will not interfere with the end of the working cylinder or piston rod.

[0069] Through the synergistic effect of the above structures, the plastic spring of the present invention achieves reliable shock absorption under heavy load conditions, while meeting multiple performance requirements such as load-bearing capacity, anti-breakage, anti-locking, anti-interference, durable rebound, and universal compatibility.

[0070] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A variable cross-section reinforced plastic spring for heavy-duty shock absorbers, comprising two sets of end mounting sections (1), wherein multiple sets of joint sections (2) are sequentially arranged axially between the two sets of end mounting sections (1), characterized in that, Each of the joint segments (2) in each group is connected by a reinforcing rib (3); The thickness of all the aforementioned stiffeners (3) is distributed in a gradually changing cross section; A stress relief groove (4) is provided at the external connection between the joint segment (2) and the reinforcing rib (3). The stress relief groove (4) is formed by the inward indentation of the external junction area of ​​the joint segment (2) and the reinforcing rib (3). The outer wall of the stress relief groove (4) has a wavy profile in the circumferential direction. The wavy profile includes multiple alternating peaks and troughs, and the outer diameter at the peak is larger than the outer diameter at the trough.

2. The variable cross-section reinforced plastic spring for heavy-duty shock absorbers according to claim 1, characterized in that, The thickness of all the reinforcing ribs (3) is distributed in a gradually changing cross section, with thinner ends and thicker middle. The thickness of the reinforcing rib (3) located in the middle position is the largest, and the thickness of the reinforcing rib (3) decreases sequentially from the middle to both ends.

3. A variable cross-section reinforced plastic spring for heavy-duty shock absorbers according to claim 1, characterized in that, The joint segment (2) consists of four sections, and the reinforcing rib (3) consists of three ribs. The thickness of the reinforcing rib (3) located in the middle position is greater than the thickness of the reinforcing rib (3) located at the edge position.

4. A variable cross-section reinforced plastic spring for heavy-duty shock absorbers according to claim 1, characterized in that, A reverse R-groove (5) is provided on the inner wall of the joint segment (2) and the reinforcing rib (3) and on the inner wall of the joint segment (2) and the end mounting segment (1). The reverse R-groove (5) smoothly transitions with the inner wall of the joint segment (2), the reinforcing rib (3) and the end mounting segment (1) to form a continuous stress flow path.

5. A variable cross-section reinforced plastic spring for a heavy-duty shock absorber according to claim 1, characterized in that, The outer wall of the joint segment (2) protrudes radially outward to form a bend (21), and each bend (21) is provided with two through holes (6) symmetrical about the center of the joint segment (2).

6. A variable cross-section reinforced plastic spring for a heavy-duty shock absorber according to claim 5, characterized in that, The through hole (6) is elliptical in shape, and the length direction of the through hole (6) extends laterally along the bend (5).

7. A variable cross-section reinforced plastic spring for heavy-duty shock absorbers according to claim 1, characterized in that, The thickness of the end mounting section (1) is less than the minimum thickness of the reinforcing rib (3), and all the reinforcing ribs (3) have the same outer diameter. The outer diameter of the end mounting section (1) is less than the outer diameter of the reinforcing rib (3).

8. A variable cross-section reinforced plastic spring for heavy-duty shock absorbers according to claim 1, characterized in that, The axial section of the stress relief groove (4) is an arc-shaped groove, a U-shaped groove or a V-shaped groove, and the root of the V-shaped groove or U-shaped groove is provided with a circular arc transition; The transition surface between adjacent peaks and troughs in the wavy profile is a smooth arc surface.

9. A variable cross-section reinforced plastic spring for a heavy-duty shock absorber according to claim 1, characterized in that, The radial height difference between the crests and troughs of the wavy profile is 5%-20% of the wall thickness of the joint segment (2).

10. A variable cross-section reinforced plastic spring for a heavy-duty shock absorber according to claim 1, characterized in that, The joint segment (2) consists of two sections, and a reinforcing rib (3) connects the two joint segments (2). The thickness of the reinforcing rib (3) is greater than the wall thickness of the joint segment (2).

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